P0601 is a "bad PCM checksum" code. What this means is that the OBD (on-board diagnostics) has experienced 6 errors while trying to communicate with the PCM (powertrain control module). The bottom line is your PCM went bad and it has these intermittent problems.

Some shady dealerships may just reset the code and the MIL light and send you on your way after charging you a couple of hundred bucks, hoping that the problem won't appear again.

There are 2 ways to fix it - you can reflash (i.e. reporogram) the PCM (which is what they probably did) or replace it.

This problem is quite common with Chrysler vehicles.

If I were you I would demand that they replace it since they tried to fix it several times and it didn't work. If your first repair was done during the warranty period I would even demand that they do it for free now. It actually may be even covered by your powertrain warranty.

You won't be able to replace the PCM yourself - you need dealer tools to program it once the new one is in place.